The objective of this proposed research is to elucidate the role of pituitary hormones in the biosynthesis of vitamin K-dependent clotting proteins. The project is the result of observations that estradiol does not cause hyperprothrombinemia or reduce the vitamin K requirement in hypophysectomized female rats. Experiments are planned to ascertain which hormone deletions are responsible for the observed effects of hypophysectomy and which steps in the elaboration of clotting protein are affected by these pituitary hormones.